Closed. Thanks.
I think it’s best you leave until the issue comes as in you get pregnant and it’s the right gender for that name. There is no point in bringing it up if you don’t know it’s ever going to be an issue. Keep it on your name list for now, and if you do get pregnant with the right gender, then it’s time to talk to you cousin. [name_m]Just[/name_m] a casual (on the phone or on facebook or whatever) "Hey we think we are going to the baby (spouses name) is that an issue for you.
The above poster gave good advice - there’s no reason to borrow trouble; you might as well wait until it’s more than a hypothetical.
I like the PPs view of waiting. I don’t think it’s ever worth throwing out a name due to a hypothetical (why give up something you love prematurely? Doesn’t make sense to me).
But honestly, I don’t think this is a big deal. I can totally see why you’re conscientious about it, because I know I would be, but with the distance factor and visit time lag between you and your husband’s cousin’s spouse, I wouldn’t worry about it much, especially if you love the name, and especially when it’s common. I think you’ll be safe 
I think it’s fine to use your husband’s cousin’s spouse’s name if she’s your age. Reversing the situation, if my husband’s cousin said they wanted to name their daughter [name_f]Sarah[/name_f], I’d be rather flattered. I have absolutely no intention of naming my child after myself. However, if the spouse is male, they may want to do a “junior” name. In which case, when you fall pregnant, you should talk to them about it. If they say they’re uncomfortable with you using that name, then don’t. But it’s not something you need to worry about until you get pregnant.
I wouldn’t bring it up to anyone unless I was actually pregnant, but I appreciate the advice. We have both loved the name a long time and I didnt want to dream about it if it was a huge no no. You know how we all like to dream of future names…